IE Conditional Comment Issue

On a new application we've made a decision to no longer support IE6, so we have a conditional comment to load a script开发者_如何学编程 that says as much.

Code is:

<!--[if lt IE 7]>
            <h2 style="color:red;">Old Version of Internet Explorer Detected</h2>
            <p style="color:red;">It appears that you're using an old version of Microsoft
            Internet Explorer.  This site is optimized for Internet Explorer 
            7 and above as well as Mozilla Firefox.  Please download a 
            newer version of <a href="https://www.microsoft.com/windows/Internet-explorer/default.aspx">
            Internet Explorer</a> or <a href="https://www.mozilla.com/firefox/">Firefox</a>
            before continuing.
            </p>
<![endif]-->

However, for one company, the comment fires, despite their use of IE7 and IE8.

Here's the access log with info removed for privacy.

10.xxx.xx.xx - - [15/Aug/2011:17:18:54 -0500] "GET /broker/js/ie6.js HTTP/1.1" 200 147 "https://xx.xxxxx.com/broker/registration" "Mozilla/4.0 (compatible; MSIE 7.0; Windows NT 5.1; Trident/4.0; .NET CLR 1.1.4322; .NET CLR 2.0.50727; .NET CLR 3.0.4506.2152; .NET CLR 3.5.30729; .NET4.0C; .NET4.0E)" "en-us"

Any ideas??

Andy

IE 7 / 8 could be using IE6 "compatibility mode"?